Lundell type rotor core structure and rotary electric machine employing the same

Abstract

A Lundell type rotor core structure and an electric rotary machine employing the same are disclosed. The rotor core structure has first and second claw pole portions alternately placed in a circumferential direction to define clearances each having a magnet mount position deviated from an axial center of each clearance and permanent magnets alternately disposed in the magnet mount positions of the clearances with respect to the axial direction of the rotor core structure for magnetizing the first and second claw pole portions in first and second magnetic polarities, respectively, wherein each of the permanent magnets allows a greater amount of magnetic fluxes to pass through one of the first and second claw pole portions than those passing through the other one of the first and second claw pole portions for minimizing harmonic component to suppress the magnetic sound.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is related to Japanese Patent Application Nos. 2005-246249 and 2006-113507 filed on Aug. 26, 2005 and Apr. 17, 2006, respectively, the contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Technical Field of the Invention [0003] The present invention relates to electric rotary machines of Lundell type rotors and, more particularly, to a Lundell type rotor core structure and an electric rotary machine employing such a Lundell type rotor core structure. [0004] 2. Description of the Related Art [0005] In general, a vehicular alternator includes a Lundell type rotor core that is comprised of a pair of pole cores each including a boss portion allowing magnetic fluxes to pass in an axial direction in an area radially inward of a field coil, a disc portion (column portion) extending radially outward from the boss portion at an axial end thereof for passing the magnetic fluxes of the magn...

AI Technical Summary

Benefits of technology

[0014] The present invention has been completed on the ground of expertise in that an electromagnetic gap associated with a claw pole portion has a magnetic flux pattern distorted along a circumferential periphery of a rotor core. Of one half area of the claw pole portion and the other half area thereof, the one half area of the claw pole portion having a weakened magnetic field in the electromagnetic gap causing a harmonic component to take place is caused to have increased magnetic fluxes upon utilizing a permanent magnet disposed between the claw pole portions. This enables a reduction in distortion of a waveform of the magnetic field caused in areas on both sides of a circumferentially center point of the claw pole portion, enabling a harmonic component such as, for instance, a third harmonic component, of the magnetic field to be minimized. This results in a reduction of vibrations of the teeth, resulting from the harmonic component of the magnetic field causing a magnetic sound in a harsh frequency band, and the magnetic sound can be minimized in a favorable fashion.

[0024] With such a structure set forth above, the electromagnetic gap can have a magnetic field pattern that is made closer to a sine wave, enabling the suppression of the magnetic sound in a simplified structure.

Problems solved by technology

This results in vibration of the teeth at high frequencies to cause a magnetic sound to be output.

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